The uses and benefits of acrylic polymer compositions are well known and documented in the literature. Generally, such compositions are desirable because they are water-based and can serve as the carrier for a wide variety of materials, including surface coatings, colorants and other substances.
Similarly, optical brightener agents, e.g., ultraviolet light absorbing ("U.V. absorbing"), compounds copolymerized within a polymer matrix are well known. For example, U.S. Pat. No. 4,882,412 to Weaver et al. discloses a polyester composition useful for molding into articles. In that disclosure, a polyester composition was copolymerized with a residue of a 7-oxy-2H-1-benzopyran-2-one compound or a 7-oxy-2H-1-benzopyran-2-imine compound, each of which are U.V. absorbing compounds.
U.S. Pat. No. 4,803,241 to Weaver et al. discloses a polymer composition comprised of a polyester or polycarbonate material copolymerized with a styrylbenzyoxazole compound.
U.S. Pat. Nos. 4,095,939 to Pacifici et al.; 2,657,188 to Butler et al.; 3,709,896 to Frischkorn et al.; and 2,657,195 to Toland et al. disclose the copolymerization of a U.V. absorbing compound with a polyester.
U.S. Pat. No. 4,177,347 to Meyer discloses a process for the preparation of distylbenzyl-oxadiazoles and the use thereof for optically brightening certain organic materials. The distilbenzyl-oxadiazoles have a carboxyl group and sulfonate group.
U.S. Pat Nos. 5,082,578 and 5,039,782 to Langer et al. disclose copolymeric whitening agents. The copolymers have a fluorescent portion and a hydrophilic portion. Hydrophilic monomers that are useful to prepare the copolymers include alkylene glycols, such as ethylene glycol, propylene glycol and butylene glycol. Other disclosed hydrophilic monomers include sugars, such as glucose, sucrose, sorbitol or glycerol.
While each of the above references discloses the incorporation of an optical brightener agent into a polymer, none of the above references disclose the incorporation of a sulfonate-containing monomer and an optical brighter agent comprising at least one polyester reactive group into a polymeric material. Nor is the incorporation of such materials into an acrylic polymer composition disclosed in any of the above references.
The incorporation of near infrared absorbing compounds into polymeric materials has also been disclosed. For example, U.S. Pat. Nos. 5,292,855; 5,336,714; and 5,423,432, each to Krutak et al., disclose water dissipatible, sulfo-containing polyesters and polyamides having copolymerized near-infrared absorbing compounds. However, when utilized in acrylic polymer compositions as contemplated by Krutak's disclosures, the copolymerized near-infrared compounds formed highly unstable compositions.
In light of the above, it would be desirable to obtain acrylic polymer compositions that incorporate polymeric materials having optical brightener agents, with or without near infrared absorbing agents. It would also be desirable to develop processes that provide stable acrylic polymer compositions that have optical brightener agents, near-infrared absorbing agents or both. Further, it would be desirable to develop methods of detecting and/or separating objects contacted with the acrylic polymer-optical brightener compositions that have optical brightener agents, near infrared absorbing agents or both.